Container, method and apparatus for making the same

ABSTRACT

A container ( 1 ) having a body and a rim ( 3 ) defining an opening for the container, the container being made of a material such as PET or PEN, is manufactured in a two-stage process. The first stage comprises injection moulding a preform ( 15 ) which has a rim ( 3 ) formed at its mouth and a continuous body-forming portion ( 32 ) extending across the preform from the inner periphery ( 19 ) of the rim, the rim having an outwardly-directed extent and including a downwardly-extending portion ( 21 ) spaced outwardly from the inner periphery and an outwardly-extending portion ( 5,6,29 ) located outwardly of the downwardly extending portion. In the second stage the preform is placed in a moulding cavity ( 56 ) of a blow moulding apparatus ( 7 ) at an elevated temperature with the preform being located by means of the rim ( 3 ). The body-forming portion expands in the cavity to form the container side wall ( 20 ) and bottom wall ( 2 ). The upper region ( 18 ) of the side wall contacts the downwardly-extending portion ( 21 ) of the rim such as to form a box section ( 25 ). The side wall ( 20 ) has at its upper side region a step ( 23 ) above which the diameter of the cavity is substantially equal to or approaches the diameter of the downwardly-extending portion ( 21 ) of the rim. Below the step ( 23 ) the diameter is less than the diameter of the inner periphery of the rim and tapers therefrom inward downwardly to the bottom wall ( 2 ) at an acute angle, whereby the containers can internest.

BACKGROUND OF THE INVENTION

This invention relates to containers moulded from plastics materials and to a method of and apparatus for making such containers.

The invention is particularly suitable for the manufacture of containers in the nature of cans or pots, preferably with lids, from polyethylene terephthalate (PET), though it is not limited to such manufacture. PET is particularly suitable for storing solvent-based contents, but is a difficult material to use in manufacture.

We have appreciated that it would be desirable to produce PET containers which use a minimum of plastics material, and yet were sufficiently strong for normal use, which occupied a minimum of space when empty for transporting, and yet which were easy to handle and use individually. When fitted with a lid the containers should stack readily and be easy to open. Such containers could be manufactured in a variety of sizes particularly in the range 250 ml to 5 litres or ½ pint to 1 gallon.

The present inventor's International Patent Application WO97/19801 describes a method of making a container using a two-stage process. In the first stage an embryo container is formed by injection moulding. In this stage the rim is essentially fully formed, but the body is not yet formed, and instead the embryo container walling takes the form of a central tube extending inwardly from the inner periphery of the rim. The embryo container is then transferred to a blow moulding machine and the walling is expanded outwardly to form the container body. The present inventor's International Patent Application WO0/46118 describes a container-with a more complex rim construction.

Other prior proposals for the manufacture of containers include Japanese Laid-Open Patent Application Sho 57-77439 (U.S. Pat. No. 4,367,821 to Holt) and International Patent Application WO99/28196 (U.S. Pat. No. 6,179,158 to Koda).

SUMMARY OF THE INVENTION

The invention in its various aspects is defined in the independent claims below, to which reference may now be made. Advantageous features are set forth in the appendant claims.

Preferred embodiments of the invention are described in more detail below with reference to the drawings. The preferred embodiments take the form of a container having a body and a rim defining an opening for the container, the container being made of a material which is susceptible to deformation when heated. The container is manufactured in a two-stage process. The first stage comprises injection moulding in an injection-moulding apparatus a preform which has a rim formed at its mouth and a continuous body-forming portion extending across the preform from the inner periphery of the rim, the rim having an outwardly-directed extent and including a downwardly-extending portion spaced outwardly from the inner periphery and an outwardly-extending portion located outwardly of the downwardly-extending portion.

In the second stage the preform is placed in a moulding cavity of a blow moulding apparatus at an elevated temperature with the preform being located by means of the rim. The body-forming portion expands in the cavity to form the container side and bottom walls. The upper region of the side wall contacts the downwardly-extending portion of the rim such as to form a box section. The rest of the body-forming portion contacts the sides of the cavity to form the side and bottom walls of the container.

In a first embodiment, the side wall has at its upper side region a narrowing side region in the form of a step above which the diameter of the cavity is substantially equal to or approaches the diameter of the downwardly-extending portion of the rim. Below the step the diameter is less than the diameter of the inner periphery of the rim and tapers therefrom inward downwardly to the bottom wall at an acute angle, whereby the containers can internest.

In a second embodiment, above the narrowing side region the container is formed with outwardly extending external ribs, the diameter of the container widening relatively rapidly in the region of the external ribs to approach the diameter of the downward extension.

The container is preferably provided with a lid which conforms with the upper surface of the rim. The lid sealingly engages the rim of the container and comprises two sealing elements one on the top and the other at the side of the portion of the lid engaging the rim. A flap may be provided at the side of the lid to assist removal thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in more detail, by way of example, with reference to the drawings, in which:

FIG. 1 is a side sectional view through a first container embodying the present invention;

FIG. 2 is a sectional detail through the rim of the container of FIG. 1;

FIG. 3 shows three nested containers, with the left-hand part of the figure in section and the right-hand part in side view;

FIG. 4 is a side sectional view through an injection moulded preform used in the manufacture of the container of FIG. 1;

FIG. 5 is a sectional view through an injection moulding machine illustrating the manufacture of the preform;

FIG. 6 is a sectional view through a blow moulding machine illustrating the initial stage in the formation of the container from the preform;

FIG. 7 is a view similar to FIG. 6 showing the end of the blow moulding operation;

FIG. 8 is a sectional view similar to FIG. 1 of the container of FIG. 1 when fitted with a lid;

FIG. 9 is a sectional detail through the rim of the container and lid in FIG. 8;

FIG. 10 is a side sectional view of the lid;

FIG. 11 is a sectional detail of the rim of the lid;

FIG. 12 is a side sectional detail showing an optional catch having a downwardly extending flap;

FIG. 13 is a side view of the region of the flap;

FIG. 14 is a detail in plan of the lidded container showing an optional rib;

FIG. 15 illustrates an alternative construction where the flap is received in a recess in the container wall;

FIG. 16 is a side view of a second container embodying the invention with a lid;

FIG. 17 is a plan view of the container lid of FIG. 16; and

FIG. 18 is a side sectional view through the container and lid of FIG. 16.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A first embodiment of the invention will now be described with reference to the drawings. FIG. 1 is a side sectional view through the finished container 1. The container is of generally cylindrical shape with sides 20 and a base 2. The base has a concave central portion to provide additional strength. The rim 3 of the container which defines its mouth has, proceeding from its inner periphery 19, an inverted U section 4, then a V shaped groove 5, and finally an inverted V section 6. Thus the rim extends generally outwardly from the inner periphery 19. All this is shown more clearly in FIG. 2. The V shaped groove 5 together with a downward extension 21 from the bottom of that groove form a downwardly-extending portion. The upper region 22 of the side wall 20 of the container contacts this downward extension 21, so as to form a box section 25. This substantially increases the strength of the rim. The inverted V section 6 then extends further outwardly of the downward extension 21, culminating in a depending flange 29.

About 15-20% of the way down the side wall 20 of the container is a step 23, where the diameter of the side wall narrows abruptly. The side wall region 18 above the step is cylindrical and has a diameter which is substantially the same as the diameter of the downward extension 21. The side wall region 24 below the step is slightly less than the diameter of the inner periphery 19 of the rim, and tapers from the step inward downwardly at a acute angle of 7 to 11 degrees. With this structure the container shown in FIG. 1 can internest with a like container. When nested, as shown in FIG. 3, the step 23 of one container rests on the rim 3 of the container below. However, the containers are easy to separate. This arises because the flanges 29 extend clear of the side wall sections 18, enabling individual containers to be grasped easily, and because the step 23 abuts the rim 3 of the container below and thus the containers cannot be forced into too tight an engagement of their tapering parts.

Nevertheless the containers are of relatively strong construction for the thickness of the material being used. The strength comes from the rim construction, which includes the box section 25, and from the existence of the step region 23 which gives strength to the upper part of the side wall of the container.

The strength may be enhanced by the use of vertical reinforcing ribs. Typically eight ribs 32 may be included, equi-spaced around the container. The presence of such ribs is indicated by cross-hatching an FIGS. 1 and 2. The ribs can be across the box section 25 and/or fill the inverted V 6.

The method of manufacturing the container of FIG. 1 will now be described. The manufacturing method is based on that described in the present inventor's International Patent Application WO97/19801. The shape of the rim is a further development of the rim described in the present inventor's International Patent Application WO00/46118. Reference may be made to both these applications for further details and variations concerning the design.

The first stage in the method is to form a preform 15.as shown in FIG. 4. The preform has the rim 3 in its final form, with the inner periphery 19, inverted U 4, V shaped groove 5, downward extension 21, inverted V 6, and flange 29. The ribs 32, if present, are also formed at this time. The wall 20 of the body of the container is not however formed at this time, but instead the preform includes a continuous dished or bowl-shaped body-forming member 32 which extends across the preform from the inner periphery 19 of the rim but which is of reduced size compared with its final form. The shape of this member 32 can be anything from approaching a flat membrane to a substantially tubular shape. In the section seen in FIG. 4, the shape adopted by the member 32 is approximately an arc of one-third of a circle.

The preform 15 is formed by injection moulding on an injection moulding machine 40, as illustrated in FIG. 5. The injection moulding machine has two main sections, namely a lower section formed by a cavity insert 42 and an upper section formed by an inner preform pin 44 and an outer preform section 46. Neck splits 48 are also provided, carried by neck split carrier plates 50, on the machine carousel 52. Plastics material is injected through an injection orifice 54 in the cavity insert 42 at the bottom centre of the preform 15. Injection moulding apparatus is very well known and thus a detailed description of such apparatus need not be given here. It should be noted however that the rim of the preform is fully formed in this operation and adopts the shape required in the final container. The body-forming portion 32 of the preform depends from the inner periphery of the rim. The preform is designed in such a manner that a straightforward vertical movement of the central mould core (preform pin 44 and section 46) will allow removal of the preform from the mould. There are no undercuts or slides in the construction of either the core or the cavity. The use of injection moulding allows the rim to be formed with high accuracy, which is necessary for good sealing of the lid.

It should be noted that in this description the preform and eventual container are assumed to be in conventional orientation, that is with the mouth at the top and the base at the bottom. The terms “up” and “down” and their derivatives should therefore be construed in this sense although in actual fact the orientation of the preform or container may be different from this.

The preform is now moved from the injection moulding machine to a blow moulding machine. A blow moulding machine is one type of pressure moulding machine; a less preferred alternative would be to employ a machine that uses suction rather than blowing. The preform is transferred to the blow moulding machine 7, shown in FIG. 6, while still hot and pliable. If it has cooled down, then it is reheated so as to be pliable. The blow moulding machine 7 has a cavity 56 defined at the sides by two movable mould halves 11 and 12 and at the bottom by a moveable base or punt 13. The top of the cavity is defined by a circular top plate 8 which carries an axially vertically moveable rod 9. The rod 9 can be lowered into the open top of the preform 15 such that it engages the sides 10 of the preform. As it descends it causes mechanical downward stretching of the container wall. The rod 9 has a hollow centre 58 which allows compressed air to travel into the cavity above the preform through angled holes 17 near the bottom of the rod. The rod 9 also has peripheral channels 60 which allow compressed air into radial channels 16 which open right at the top of the cavity near the top of the side wall 20 of the container.

The rim 3 is held fast in the blow mould. More particularly, the V groove 5 and the inverted V groove 6 are supported by the mould halves, though in the case of the outermost groove 6 only partially so. The remainder of the groove 6 is fitted into a continuous metal ring 14, split into two, such that it can subsequently lift the finished moulding clear of the blow mould 7. The metal ring 14, or neck splits, are carried on neck split carrier plates 64.

Thus the sequence is that first the two blow mould halves 11,12 close around the pliable preform 15, at an elevated temperature, and the metal ring 14. The circular top plate 8 is lowered onto the mould, which it touches at the outside face of the inner U groove 4. Then the stretch rod 9 is lowered to force the material 32 which is to constitute the container walls towards the base 13 of the mould cavity 56. Simultaneously, compressed air is introduced into the hollow centre 58 and the channels 60 of the stretch rod 9. It emerges both from the holes 16 at the top and the angled holes 17 at the bottom. The holes 16 at the top are larger than those 17 at the bottom and also nearer the source of the compressed air. This causes the plastics material at the top of the preform to move outwardly until it contacts the side of the blow mould cavity, covering the base of the inverted U 4 as it does so. This thus forms the larger diameter portion 18, as well as the box section 25, the latter being formed by the side wall of the container bearing against the downward extension 21 to complete the box section shape.

As the compressed air continues to blow, it also emerges from the holes 17 at the lower end of the rod 9, and now forms the remainder of the container by compressing the still-soft plastics material of the preform hard against the metal sides of the blow mould. This continues to be assisted by the mechanical strengthening caused by the stretch rod 9. The fully-formed container in the blow moulding machine is shown in FIG. 7.

The shape of the mould cavity 56 is such as to impart the desired shape to the container walls 20. Thus the cavity 56 has a narrow side wall section or step 66 about one-fifth or one-sixth of the way down the side wall. Above the step 66 the diameter of the cavity is approximately the same as the downward extension 21 of the rim 3 of the preform 15 when located in position in the mould cavity. Below the step 66 the diameter is less than the diameter of the inner periphery 19 of the rim 3 of the preform when located in position in the mould cavity. Descending further down the cavity, the cavity well tapers inwardly at an acute angle of 7 to 11 degrees, until it reaches the bottom wall of the cavity.

Once the material has cooled and solidified, the blow mould opens and the container is lifted out. The container is lifted out by the rim 3, and this can be facilitated by mould rings which form and engage with an undercut 28 (see FIG. 2) on the outer face of the rim 3, these rings themselves splitting into two to release the product.

The container 1 is preferably fitted with a lid 26 as shown in FIGS. 8 and 9. The lid 26 is flat across the main central part but is shaped in the region of its periphery to conform with the upper surface of the rim 3 of the container 1. To this end the lid 26 first has a ridge 70 which conforms over the top of the U section 4, now forming the box section 25, and then has a downwardly extending wedge shape 27 which mates with the V-groove 5. Because of the rigid nature of the material, however, the two interlocking tapers between the wedge shape 27 and the V-groove 5 will not retain the closure or lid 26, which, due to the radial compressive force of the V groove, will gradually lift out from the sealing faces.

Thus, as shown in FIG. 9, the lid 26 is retained on the container 1 by a downwardly extending flange 72 depending from the periphery of the lid and conforming to the upper and outer faces of the rim in the region of the inverted V groove 6. The flange 72 thus fits around the flange 29. The flange 72 furthermore carries a detent in the form of an inwardly-facing rib 74 on its inner face. This inwardly-facing rib 74 engages with the undercut 28 which was formed on the injection moulding machine forming a mating detent. The inside diameter of the lid outer flange 72 is smaller than the outside diameter of the flange 29 just above the undercut 28.

The sealing is thus provided by the combination of two sealing structures at an angle of 90 degrees to each other, namely the wedge shape 27 and the V-groove 5 on the one hand, and the rib 74 and the undercut 28 on the other.

Sectional views of the lid alone are shown in FIGS. 10 and 11.

In order to facilitate release and removal of the lid, a flap 35 may be provided as shown in FIGS. 12 to 15. As best seen in FIG. 12, the flap extends downwardly from the periphery of the flange 72 at selected points identified by an external rib 37. The flap hinges at 36. The lower outwardly-curved portion of the flap is accessed by inserting the user's finger beneath it, and pulling in an upward direction, at which point the flap becomes a hinged lever. It is restrained from travelling beyond 90 degrees to the container, i.e. upwardly of the horizontal, by the rib 37. Further upward movement of the flap 35 causes the outer flange 72 of the lid to become detached from the underside of the flange 29 of the rim. This permits removal of the lid by peeling the flange 72 from the flange 29 of the container 1. FIG. 13 shows a side view and FIG. 14 a top view of the region of the flap 35.

An alternative arrangement is shown in FIG. 15, where the flap or handle 35 is larger and has a portion 38 which fits in a recess 39 near the top of the container.

The flap may be configured to have a “tamper evident” membrane, visually indicating that it has already been used previously to open a container.

The container of FIG. 1 is formed with the box section 25 at the top inner face which provides structural strength and permits large hoop stresses to be developed between the wedge shape 27 and the V-groove on the container. The strength is further aided by the step 23 and by the taper below the step to the bottom of the container.

The container can internest as shown in FIG. 3 which illustrates three internesting containers. Each container sits with its step 23 sitting on the upper surface of the rim 3 of the container below it. Thus the outer part of the tapering section cannot become too firmly wedged in the inner part of the tapering section of the container below it. Separation of the containers is further facilitated by the fact that the outer part of the rim extends outwardly of the container wall, making it easy for the user to grab hold of two adjacently stacked containers so as to separate them.

Thus the advantageous features of adequate strength, ability to nest, and ease of separation, while using a minimum of plastics material, are provided by the co-operative effects of the box structure giving strength to the ring, and the step and taper giving strength to the body while the step allows one container to rest on the rim of another. Ease of separation is assisted by the outwardly-extending portion of the rim with its downwardly-extending peripheral flange which facilitates manual gripping on the containers for separation.

The container is preferably made from polyethylene terephthalate (PET), for which the process is particularly suitable. Other thermoplastic resins may however be used, including polyethylene naphthalate (PEN), and also PET and PEN blends, in both the crystalline and amorphous structures of these two materials. Also, other rigid plastics including polyvinyl chloride (PVC), polycarbonate, acrylics, and various polyolefins including polypropylene and high density and low density polythene. In principle any material susceptible to deformation when heated may be used, but the method is particularly advantageous with PET etc.

The containers can be formed as pails, buckets, or cans and are particularly suitable for enclosing solvent-based contents for storage for long period without solvent loss. They may, in particular, be used as cans for paints and other coating materials. The container itself is made as a unitary element without the need for welds, which are costly and can be unreliable. The containers can be formed accurately of PET, which requires blow moulding to give the biaxial stretching necessary for optimum strength. Despite having a reasonably narrow taper, the containers can be nested without jamming. Finally, the container can be repeatedly resealed and yet can be opened again without the need for special tools.

A second embodiment of the invention is illustrated in FIGS. 16 to 18. This embodiment is similar to the first embodiment and thus only the differences will be described.

In the second embodiment the step 23 and the upper section 18 of the container side wall of the first embodiment are replaced by a strongly tapering section 80 with external ribs 82. Thus in the region of the ribs, the diameter of the container widens relatively rapidly to approach the diameter of the downward extension. The external ribs have horizontal lower peripheries so that, when nested, the ribs sit on the top of the rim of the container below, again stopping jamming from taking place. In other respects the container is the same as the container of the first embodiment.

Although preferred embodiments of the invention have been described and illustrated, by way of example, many modifications may be made to the method, apparatus and containers described. 

1. A container having a body and a rim defining an opening for the container, the container being made of a material which is susceptible to deformation when heated, the container comprising: a rim formed at the mouth of the container, the rim having an outwardly-directed extent and including a downwardly-extending portion spaced outwardly from the inner periphery and an outwardly-extending portion located outwardly of the downwardly-extending portion; a container side wall and bottom wall, the upper region of the side wall contacting the downwardly-extending portion of the rim; characterized in that: the upper region of the side wall contacts the downwardly-extending portion of the rim such as to form a box section; and the side wall of the container has at its upper side region a narrowing side wall section above which the diameter of the side wall is substantially equal to or approaches the diameter of the downwardly-extending portion of the rim and below which the diameter is less than the diameter of the inner periphery of the rim and tapers therefrom inward downwardly to the bottom wall at an acute angle, whereby like containers can internest.
 2. A container according to claim 1, in which the container material comprises polyethylene terephthalate (PET), polyethylene naphthalate (PEN), or a PET and PEN blend.
 3. A container according to claim 1, in which the rim has an outwardly-extending portion radially beyond the downwardly-extending portion.
 4. A container according to claim 3, in which the outwardly-extending portion has a peripheral flange to assist in manual grasping of the container when nested with another like container.
 5. A container according to claim 1, in which the rim has a radially inner inverted U section, then a V shaped groove, and finally an inverted V section.
 6. A container according to claim 5, in which the downwardly-extending portion extends downwardly from the V shaped groove.
 7. A container according to claim 1, in which said acute angle is between 7 and 11 degrees.
 8. A container according to claim 1, further including radially-extending reinforcing ribs spaced around the periphery of the rim of the container.
 9. A container according to claim 1, in which the narrowing side region comprises a step above which the side wall is of substantially constant diameter.
 10. A container according to claim 1, in which above the narrowing side region the container is formed with outwardly extending external ribs, the diameter of the container widening relatively rapidly in the region of the external ribs to approach the diameter of the downward extension.
 11. A container according to claim 1, further comprising a lid for the container, the lid conforming with the upper surface of the rim.
 12. A container according to claim 11, in which the lid sealingly engages the rim of the container and comprises two sealing elements one on the top and the other at the side of the portion of the lid engaging the rim.
 13. A container according to claim 11, including a flap at the side of the lid to assist removal thereof.
 14. A method of manufacturing a container having a body and a rim defining an opening for the container, the container being made of a material which is susceptible to deformation when heated, the method comprising the steps of: injection moulding in an injection-moulding apparatus a preform which has a rim formed at its mouth and a continuous body-forming portion extending across the preform from the inner periphery of the rim, the rim having an outwardly-directed extent and including a downwardly-extending portion spaced outwardly from the inner periphery and an outwardly-extending portion located outwardly of the downwardly-extending portion; placing the preform in a moulding cavity of a pressure moulding apparatus at an elevated temperature with the preform being located by means of the rim; and moving the body-forming portion in the pressure moulding apparatus downwardly and outwardly whereby the body-forming portion expands in the cavity to form the container side and bottom walls, the upper region of the side wall contacting the downwardly-extending portion of the rim, and the rest of the body-forming portion contacting the sides of the cavity to form a shape defined by the interior shape of the cavity; characterized in that: the upper region of the side wall contacts the downwardly-extending portion of the rim such as to form a box section; and the interior of the moulding cavity of the pressure moulding apparatus is shaped to define the side and bottom walls of the container with the cavity having at its upper side region a narrowing side wall section above which the diameter of the cavity is substantially equal to or approaches the diameter of the downwardly-extending portion of the rim and below which the diameter is less than the diameter of the inner periphery of the rim and tapers therefrom inward downwardly to the bottom wall at an acute angle, whereby the resultant containers can internest.
 15. A method according to claim 14, in which the container material comprises polyethylene terephthalate (PET), polyethylene naphthalate (PEN), or a PET and PEN blend.
 16. A method according to claim 14, in which the injection moulding step forms the rim with an outwardly-extending portion radially beyond the downwardly-extending portion.
 17. A method according to claim 16, in which the outwardly-extending portion has a peripheral flange to assist in manual grasping of the container when nested with another like container.
 18. A method according to claim 14, in which the injection moulding step forms the rim with a radially inner inverted U section, then a V shaped groove, and finally an inverted V section.
 19. A method according to claim 18, in which the downwardly-extending portion extends downwardly from the V shaped groove.
 20. A method according to claim 14, in which said acute angle is between 7 and 11 degrees.
 21. A method according to claim 14, further including radially-extending reinforcing ribs spaced around the periphery of the rim of the container.
 22. A method according to claim 14, in which the cavity of the pressure moulding apparatus is shaped such that the narrowing side region comprises a step above which the cavity is of substantially constant diameter.
 23. A method according to claim 14, in which the cavity of the pressure moulding apparatus is shaped such that above the narrowing side region the container is formed with outwardly extending external ribs, the diameter of the container widening relatively rapidly in the region of the external ribs to approach the diameter of the downward extension.
 24. A method according to claim 14, in which the pressure moulding apparatus is blow moulding apparatus.
 25. A method according to claim 14, in which the step of moving the body-forming portion is assisted by mechanical stretching of the body-forming portion in the pressure moulding apparatus.
 26. A method according to claim 14, further comprising the step of providing a lid for the container, the lid conforming with the upper surface of the rim.
 27. A method according to claim 26, in which the lid sealingly engages the rim of the container and comprises two sealing elements one on the top and the other at the side of the portion of the lid engaging the rim.
 28. A method according to claim 26, including a flap at the side of the lid to assist removal thereof.
 29. Apparatus for manufacturing a container having a body and a rim defining an opening for the container, the container being made of a material which is susceptible to deformation when heated, the apparatus comprising: an injection-moulding apparatus adapted to injection-mould a preform which has a rim formed at its mouth and a continuous body-forming portion extending across the preform from the inner periphery of the rim, the rim having an outwardly-directed extent and including a downwardly-extending portion spaced outwardly from the inner periphery and an outwardly-extending portion located outwardly of the downwardly-extending portion; a pressure moulding apparatus having a moulding cavity; means for placing the preform in the moulding cavity of the pressure moulding apparatus at an elevated temperature with the preform being located by means of the rim; and means in the pressure moulding apparatus for moving the body-forming portion downwardly and outwardly whereby the body-forming portion expands in the cavity to form the container side and bottom walls, the upper region of the side wall contacting the downwardly-extending portion of the rim, and the rest of the body-forming portion contacting the sides of the cavity to form a shape defined by the interior shape of the cavity; characterized in that: the cavity is so shaped that the upper region of the side wall contacts the downwardly-extending portion of the rim such as to form a box section; and the interior of the cavity in the pressure moulding apparatus is shaped to define the side and bottom walls of the container with the cavity having at its upper side region a narrowing side wall section above which the diameter of the cavity is substantially equal to or approaches the diameter of the downwardly-extending portion of the rim and below which the diameter is less than the diameter of the inner periphery of the rim and tapers therefrom inward downwardly to the bottom wall at an acute angle, whereby containers formed by the apparatus can internest.
 30. Apparatus according to claim 29, in which the injection moulding apparatus forms the rim with an outwardly-extending portion radially beyond the downwardly-extending portion.
 31. Apparatus according to claim 30, in which the outwardly-extending portion comprises a peripheral flange to assist in manual grasping of the container when nested with another like container.
 32. Apparatus according to claim 29, in which the injection moulding apparatus forms the rim with a radially inner inverted U section, then a V shaped groove, and finally an inverted V section.
 33. Apparatus according to claim 32, in which the downwardly-extending portion extends downwardly from the V shaped groove.
 34. Apparatus according to claim 29, in which said acute angle is between 7 and 11 degrees.
 35. Apparatus according to claim 29, in which the injection moulding apparatus is further shaped to form radially-extending reinforcing ribs spaced around the periphery of the rim of the container.
 36. Apparatus according to claim 29, in which the cavity of the pressure moulding apparatus is shaped such that the narrowing side region comprises a step above which the cavity is of substantially constant diameter.
 37. Apparatus according to claim 29, in which the cavity of the pressure moulding apparatus is shaped such that above the narrowing side region the container is formed with outwardly extending external ribs, the diameter of the container widening relatively rapidly in the region of the external ribs to approach the diameter of the downward extension.
 38. Apparatus according to claim 29, in which the pressure moulding apparatus is blow moulding apparatus.
 39. Apparatus according to claim 29, in which the pressure moulding apparatus includes means for mechanical stretching of the body-forming portion.
 40. Apparatus according to claim 29, further comprising means for forming a lid for the container, the lid conforming with the upper surface of the rim.
 41. Apparatus according to claim 40, in which the lid sealingly engages the rim of the container and comprises two sealing elements one on the top and the other at the side of the portion of the lid engaging the rim.
 42. Apparatus according to claim 40, including a flap at the side of the lid to assist removal thereof.
 43. A container manufactured using the method of claim
 14. 